1. Field of the Invention
This invention relates generally to network management and specifically relates to troubleshooting network devices that use the Fibre Channel (“FC”) protocol.
2. Description of Related Art
Network devices occasionally malfunction. Such malfunctions can result in the network devices going down, in congestion of traffic on the network and in other negative effects. When such malfunctions occur, network managers need to analyze traffic on one or more network devices in order to troubleshoot the problem. Moreover, network traffic should be analyzed in other situations, such as during a system upgrade, when bringing up a network, for monitoring a network, etc.
Several limitations may be encountered when configuring networks such as local area networks, storage area networks and the like. There are a variety of network devices, such as routers, switches, bridges, etc., which may be used to configure such networks. Some of these network devices have greater capabilities than others. For example, some devices may readily be configured to support logical networks superimposed upon a physical network (e.g., virtual local area networks (“VLANs”) or virtual storage area networks (“VSANs”)) and some may not.
In order to allow multiple VLANs to share a single inter-switch link on the underlying physical topology, the interswitch link protocol (“ISL”) was developed at Cisco Systems. See for example U.S. Pat. No. 5,742,604, entitled “Interswitch link mechanism for connecting high-performance network switches,” Edsall, et al., issued on Apr. 21, 1998 to Cisco Systems, Inc., which is hereby incorporated by reference for all purposes. ISL provides an encapsulation mechanism for transporting packets between ports of different switches in a network on the basis of VLAN associations among those ports. (The terms “frame” and “packet” are equivalent as used herein.)
FC protocol is increasingly used for storage area networks and similar networks. One such device used as a fabric network device for storage area networks is a Multi-layer Data Switch (“MDS”), manufactured by Cisco Systems, Inc. Data ingress and egress the MDS in FC protocol via FC ports. Accordingly, when a network manager needs to troubleshoot a problem with a network device that is using FC protocol, the device used by the network manager must be able to capture and analyze frames in FC protocol.
Currently, devices known as FC analyzers are available for capturing and analyzing data from an FC port. An FC analyzer is configured to receive FC frames from a network device and to allow an engineer, network administrator, etc., to view and analyze the FC frames. Analysis of the FC frames and knowledge of types of errors associated with the FC frames can be useful in identifying the underlying problems with the network.
However, FC analyzers are normally interposed between two switches in an FC network. Therefore, connecting the FC analyzer causes disruption of the network and user “down time.” Moreover, network disruption can change the setup environment and consequently make a problem more difficult to debug. In addition, the people troubleshooting the FC network may not be at the same location as, for example, a switch believed to be causing a problem. It would be desirable to have more flexible devices and methods for the analysis of FC networks as compared to the prior passive FC Analyzer technology.